Search for $XYZ$ states in ${\rm Y}(1S)$ inclusive decays

Abstract

The branching fractions of the ${\rm Y}(1S)$ inclusive decays into final states with a $J/\psi$ or a $\psi (2S)$ are measured with improved precision to be $\text{BR}({\rm Y}(1S)\to J/\psi +\mathrm{anything})=(5.25\pm 0.13(stat.)\pm 0.25(syst.))\times 10^{-4}$ and $\text{BR}({\rm Y}(1S)\to \psi (2S)+\mathrm{anything})=(1.23\pm 0.17(stat.)\pm 0.11(syst.))\times 10^{-4}$. The first search for ${\rm Y}(1S)$ decays into $XYZ$ states that decay into a $J/\psi$ or a $\psi (2S)$ plus one or two charged tracks yields no significant signals for $XYZ$ states in any of the examined decay modes, and upper limits on their production rates in ${\rm Y}(1S)$ inclusive decays are determined.

Comments: 10 pages, 7 figures, 3 tables